Did you try to tweet a URL on Twitter - and then found that you don't have enough space to write the actual message?
Or did you ever think of sending a URL to someone with the intent of hiding actual address of the URL from the recipient?
Or did you want a URL which people could easily remember?
Well, the answer to all of these questions is a "URL Shortener".
To understand this better, check out this link. (http://bit.ly/5rdxu8)
Well, this is the the address of my blog - http://vyanks.blogspot.com/ - in a shortened format.
Doesn't this sound like an alter ego?
Check out this interesting article which explains how URL shortening works.
And if you want to shorten your URL, then you can use this website.